Loosely coupled wireless power systems include a power transfer unit (e.g., a charging device) and one or more power receive units (e.g., a cellphone, a laptop, etc.) to be charged. When non-compliant objects are present within, near, or around the charging region of the power transfer unit, electrical energy may be lost in the wireless power system. The lost electrical energy may harm a user, damage a device or object, start a fire, etc. As such, it is desirable to detect when the power system experiences a loss in power and to respond appropriately.